Difference between revisions of "Open Problems:63"

From Open Problems in Sublinear Algorithms
Jump to: navigation, search
m
Line 5: Line 5:
 
}}
 
}}
  
Let $G = (V, E)$ be a graph. Fix a monotone  submodular function $f : 2^E \rightarrow \mathbb{R}$. A maximum submodular matching $M$ is a subset of $E$ that forms a matching and maximizes $f(E)$.  
+
Let $G = (V, E)$ be a graph. Fix a monotone  submodular function $f : 2^E \rightarrow \mathbb{R}$. A maximum submodular matching $M$ is a subset of $E$ that forms a matching and maximizes $f(E)$. Suppose the graph edges are streaming. It is known that we cannot compute a maximum weight matching in one pass and $n \operatorname{polylog}(n)$ space to a better approximation than $\frac{e}{e-1}$. Can we show a stronger lower bound for maximum ''submodular'' matchings? A conjecture is that it will be hard to get a better than 2-approximation in one pass with the same space constraints.  
 
 
Suppose the graph edges are streaming. It is known that we cannot compute a maximum weight matching in one pass and $n \operatorname{polylog}(n)$ space to a better approximation than $\frac{e}{e-1}$. Can we show a stronger lower bound for maximum ''submodular'' matchings?  
 
 
 
A conjecture is that it will be hard to get a better than 2-approximation in one pass with the same space constraints.  
 
  
 
A related question  (due to Deeparnab Chakrabarty): Is there an instance-wise gap between MWMs and MSMs in the stream setting?
 
A related question  (due to Deeparnab Chakrabarty): Is there an instance-wise gap between MWMs and MSMs in the stream setting?

Revision as of 04:16, 4 June 2014

Suggested by Amit Chakrabarti
Source Bertinoro 2014
Short link https://sublinear.info/63

Let $G = (V, E)$ be a graph. Fix a monotone submodular function $f : 2^E \rightarrow \mathbb{R}$. A maximum submodular matching $M$ is a subset of $E$ that forms a matching and maximizes $f(E)$. Suppose the graph edges are streaming. It is known that we cannot compute a maximum weight matching in one pass and $n \operatorname{polylog}(n)$ space to a better approximation than $\frac{e}{e-1}$. Can we show a stronger lower bound for maximum submodular matchings? A conjecture is that it will be hard to get a better than 2-approximation in one pass with the same space constraints.

A related question (due to Deeparnab Chakrabarty): Is there an instance-wise gap between MWMs and MSMs in the stream setting?